Projectile fuse



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p W. J. HAWKINS PROJECTILE FUSE Filed June 18. 1921 "lll'i Illllllllll" [N VENTOR A TTORNE y Patented Get. 28, 1924.

"E1. STATES P A T if;

WILFORD J'. HAWKINS, OF MONTCLAIR, NEW JERSEY.

PROJEGTILE FUSE.

Application filled June 18, 1921. Serial No. 478,503.

' a citizen of the United States, residing at Montclair, county\ of Essex, and State of .1 New Jersey, have invented a new and useful Improvement in Projectile Fuses, of which the following is a specification.

This invention relateslto an improvement in projectile fuses and it has for its main object the production of a fuse more reliable and eflicient than those heretofore used, and especially designed to control point of burst at any desired distance from a gun in which it is used irrespective of variations in projectile velocity and elapsed time. The invention consists in certain constructions and combinations which will be herein-after fully described and then specifically pointed out in the claims hereunto appended.

In the accompanying drawings, which form a part of this specification and in which like characters of reference indicate the same or like parts, Fig. 1 is a central sectional view of a fuse constructed in accordance with the invention, but illustrated on a scale exceeding actual size; Fig. 2 is a sectional view taken on the line 22 in Fig. 1; Fig. 3 is a fragmentary sectional view taken on the line 3-3 in Fig. 2; and Fig. 4 is an exterior view of the device shown in Fig. 1, but illustrated on a scale somewhat smaller than actual size.

The particular device selected to illustrate the invention is but one of many possible concrete embodiments of the same, and the device may be widely varied in construction within the scope of the claims; the invention, therefore, is not to be restricted to the precise details of the structure shown and described.

Referring to the drawings, there is provided a casing within the limits of which the entire mechanism is housed. This casing consists of a base 5 adapted to be screwed into the forward end of a projectile shell in the usual manner, a graduated section 6 2. spacing section 7, and a nose 8. The base 5 is provided with an annular groove 9, and thegraduated section '6 is provided with three stud screws 10 engaging the groove 9. By means of the con struction just described, the graduated section 6 may be rotated on the base 5 for the purpose of setting the fuse. The graduated section 6 and the spacing section 7 of the casing are screwed together at 11 and held against accidental displacement by means of a small set screw 12. The nose 8 is adjustably screwed and piloted into the spacing section 7 at 13 and is held against accidental displacement by means of a small set screw 14;. While as shown, the exposed walls of'the casing may be strictly conical in form, they will preferably be slightly curved on the radius most e cient in the interest of flat trajectory.

Mounted within the casing is a rotational inertia member consisting of a fly wheel 15 which is threaded on an enlarged section of a spindle 16. The lower end of this spindle is hardened and rests upon a hardened steel ball 17, seated in a pocket formed in a hardened steelplug 18 screwed and piloted into the base 5 before referred to. The purpose of the ball 17 and the hardened steel contacting parts is to provide a minimum 00- efficient of friction between the spindle and its bearing, and to resist the tremendous rearward thrust exerted by the fly wheel and spindle during set back and projectile acceleration, and thereby prevent derangement of the mechanism by set back. Similarly, the upper end of the spindle 16 is hardened and contacts with a small hard ened steel ball 19 seated in a pocket formed in the nose 8 which is constructed of hardened steel. The purpose of the ball 19 and its contacting hardened steel parts is to provide a minimum co-efiicient of friction and to resist the lesser forward thrust of the fly wheel and spindle during projectile retardation.

The base 5 is provided with a chamber 20 filled with a magazine charge-of powder held in position by means of a plug 21 screwed into the base 5 and provided with a flash aperture 22. The base 5 is further provided with a flash aperture 23 establishing communication between the magazine charge and a suitable primer indicated at 24, held in position by means of a screw plug 25. The base is further provided with a spring pressed firing pin 26 normally held in armed position. The parts just described are of well known character and a more detailed description thereof is deemed unnece'ssary. The firing pin 26 has an undercut head 27 projecting above the upper face of the base 5. This undercut head is normally engagled, and the pin is held in armed position y two sears, one being a centrifugal sear 28 pivoted on a stud 29 secured in the base 5. The centrifugal sear 28 is further provided with a light leaf spring 30, one end of which is fixed to the scar and the other end in contact with a stud 31 in the base. In addition to the centrifugal sear 28 there is provided a timing sear 32 pivoted on a stud 33 carried by the base 5. One end of thetiming sear 32 engages the underout head 27of the firing pin 26. At its other end the timing sear 32 has an upturned lug 34 lying outside the lower edge of a sear dial 35, provided with a timing notch 36. The same end of the timing sear 32 has a curved surface normally engaging the head of a safety plunger 36' mounted in a suitable aperture 37 formed in the base 5 and operative normally to prevent rotation of the timing sear 32 on its pivot stud 33. The plunger 36 is normally held in the position shown in Fig. 3 b means of a small wire 38 passing through 1t. The safety plunger 36 prevents the timing sear 32 from releasing the firing pin 26 until after the wire 38 has been sheared off by relative rearward movement of the plunger during set back. When set back occurs, the timing sear 32 is held against rotation on the stud 33 by the engagement of its lug 34 with the sear dial 35 until the dial notch 36 comes into register with the lug 34 and permits the latter to paw through under the influence of centrifugal force acting on the sear 32, aided by the wedging action of the inclined undercut head 27 of the firing pin 26. The centrifugal sear 28 with its spring 30 is so constructed that it cannot release the firing pin until high angular velocity of the projectile has been attained. The two sear devices just described thus provide double safety devices for preventing premature firing, the one controlled by set back and the other by maximum angular velocity of the rojectile.

It w1ll of course be understood that the rifling of the gun in which the projectile carrying the fuse is used positively causes the projectile to rotate on its own axis at high angular velocity determined by the pitch of the rifiing and the force exerted by the propelling charge. The rotation of the inertia member, however, mounted as it is in almost frictionless bearings, is but little influenced by the forces producing high angular velocity of the projectile. The projectile attains its maximum angular velocity at or adjacent the muzzle of the gun in which it is used, while the rotational inertia member does not attain its maximum angular velocity until the point of burst is reached. The differential angular velocity existing between the projectile and the rotational inertia member when in action, and therefore between the'fuse casing and the rotational inertia member, provides motive power which is used for the purpose of controlling firing mechanism interposed between the casing and the inertia member and which at the proper time releases the firing pin 26. It will be understood of course that the firing pin 26 and the sears 28 and 32 form.- a part of this firing mecha- IllSIIl.

The sear dial 35 before referred to is dish-shaped, surrounds the fly wheel 15, and is mounted on a ball bearing 39 interposed between it and an enlarged section of the spindle 16. At its upper end it is provided with a gear wheel 40 in mesh with reduction gearing indicated generally by the reference character 41. This reduction gearing is in constant mesh with a long pinion 42 formed on a sleeve 43 surrounding the 'upper end of the spindle 16. The reduction gearing is carried by a frame 44 fitting and rotatable with the spacing section 7 of the casing.

Like the firing pin 26, the sear dial 35 is provided with two safety devices, one locking it to the casing until set back occurs, and the other locking it to the casing until high angular velocity of the projectile has been attained. The first of these devices includes a plunger 45 mounted in a bearing 46 carried by the frame 44 before referred to. The plunger is normally held in "the position shown in Fig. 1 by means of a shear wire .47 of the usual type. The plunger adjacent its lower end is provided with an annular groove 48 and its end just below this groove normally engages an offset tongue 49 struck up from the body of the sear dial, to prevent relative rotation of the casing and dial. It is necessary that the sear dial be thus locked to the casing so that when the major part of the casing is rotated on its base to set the fuse, the notch 36 of the sear dial will be carried to itsproper position. When set back occurs, the

plunger 45 is given a relative rearward movement which shears off the wire 47 and brings the groove 48 in register with the tongue 49 and frees the casing and dial at this point. This, however, does not permit relative rotation of the casing and sear dial because the centrifugal safety device does 7 not release it until maximum angular velocity of the projectile is attained. This centrifugal safety device consists of an arm 50 engaging a slot 51 in the sear dial. The arm is pivoted at 52 to a lug depending from the frame 44 before referred to, and is provided with a light leaf s ring'53, the free end of which engages tii the graduated section 6 of the casing. When high angular velocity of the projectile is attained, the arm 50 is by centrifugal force swung out clear of the sear dial and the latter is then free to come into operation.

As shown in Fig. 1, the lower end of the sleeve 43 is out of engagement with a nare inside of rowly tapered section 54 of the spindle 16. When set back occurs, the sleeve 43 is given a relative rearward movement which causes it to j-amon or be clutched to the tapered section 54 of the spindle. This engagement sets the reduction gearing into operation.- The reduction caring is designed-to produce a slight ifierential angular velocity of the casing and sear dial which may be 1 R. I, M. It is to be understood, however, H.185, this differential movement may be varie By means of the mechanism just described, the point of burst is determined by the setting of the fuse and the number of revolutions it makes up to that point. The rifling of the gun of course is fixed, and its pitch determines the number of revolutions the projectile will make in a given distance irrespective of the time elapsing during the flight of'the projectile through that distance.

The setting of the fuse, therefore, determines the point of burst by distance and not by elapsed time, and this automatically compensates for variation in projectile velocity and makes the device more accurate in action than a time fuse can be.

What is claimed is:

1. In a projectile fuse, the combination with a casing, of a rotational inertia member, and firing mechanism including a sear disk and reduction gearing interposed between said casing and said member and controlled by their differential angular velocity and including a clutch device operated by set back, and externally accessible means for setting the fuse for any desired point of action.

2. In a projectile fuse, the combination with a casing, of a rotational inertia member, and firing mechanism including a sear disk and reduction gearing interposed between said casing and said member and controlled by their difi'erential angular velocity and including a clutch device operated by set back, and safety means for preventr ing fuse action until after set back.

3. In a projectile fuse, the combination with a casing, of a rotational inertia member, and firing mechanism including a sear disk and reduction gearing interposed between said casing and said member and controlled by their difl'erential angular velocity and including a clutch device operated by set back, and safety means for preventing fuse action until after the projectile has attained a high rate of rotation.

4. In a projectile fuse, the combination with a casing, of a rotational inertia member, and firing mechanism including a sear disk and reduction gearing interposed between said casin and said member and controlled by their differential angular velocity and including a clutch device operated by set back, and means for automatically compensating .for high or low projectile velocity.

5. In a projectile fuse, the combination with a casing, of a rotational inertia member, and firing mechanism including a sear disk and reduction gearing interposed between said casing and said member and controlled by their differential angular velocity and including a clutch device operated by set back, and a sear disk locked to said casing until after set back.

6. In a projectile fuse, the combination with a casing, of a rotational inertia member, and firing mechanism including a sear disk and reduction gearing interposed between said casing and said member and controlled by their differential angular velocity and including a clutch device operated by set back, and a sear disk locked to said casing until after the projectile has attained a high rate of rotation.

7. In a projectile fuse, the combination with a casing, of a rotational inertia member, and firing mechanism including a sear disk and reduction gearing interposed be.- tween said casing and said member and controlled by their dilferential angular velocity and including a clutch device operated by set back.

8. In a projectile fuse, the combination with a casing, of a rotational inertia member, and firing mechanism including sear disk reduction gearing interposed between said casing and said member and controlled by their differential angular velocity and including a clutch member constantly in mesh with the sear disk reduction gearing and operatively connected with said inertia member by set back.

9. In a projectile fuse, the combination with a casing, of a rotational inertia member, firing mechanism including a sear disk and reduction gearing interposed between said casing and said member and controlled by their differential angular velocity, and including a clutch device operated by set back and a single ball interposed between said casing and the rear end of said member and capable of resisting the rearward thrust of. said member and of providing a minimum co-efiicient of friction during set' back and projectile acceleration.

10. In a projectile fuse, the combination with a casing, of a rotational inertia member, firing mechanism including a sear disk and reduction gearing interposed between said casing and said member and controlled by their differential angular velocity, and

including a clutch device operated by set back-and a single ball interposed between said casing and the forward end of said member and capable of resisting the forward thrust of said member and of providing a minimum co-eflicient of friction during projectile retardation.

11. In a projectile fuse, the combination with a casing, of a rotational inertia member, and firing mechanism including a sear disk and reduction gearing interposed between said casin and said member and including. a clutc device operated by set back, and a scar disk and gearing connecting said disk with said member for producing a differential angular velocity of said casing and said disk.

12. Ina projectile fuse, the combination with a casing, of a rotational inertia member, firingmechanlsm including a scar disk and reduction gearing interposed between said casing and said member and arranged to be connected with both by set back and thereafter controlled by their difi'erential angular velocity and including a clutch device operated by set back, and safety means for preventing fuse action until after set back and the projectile has attained a high rate of rotation and means for automatically compensating for high or low projectile. velocity, a single ball at each end of said member for resisting member thrust and for providing a minimum co-efiicient of friction, and externally accessible means fol setting the fuse for any desired point of action.

In testimony whereof, I have signed my name to this specification.

' WILFORD J. HAWKINS. 

